To back-up what Larus Marinus wrote in an early post, there is nothing new under the sun, especially when it comes to combatives. Every generation tends to hold itself higher up on the development ladder than other generations, especially when compared to the ancients.

In history classes we were introduced to this as a concept called, "The Sin of Present-ism."

One problem is that documents, and other records, have been destroyed by time, and the body of training and doctrine that defined various schools of combat have been broken by societal change. As a result, we keep re-discovering fire, again.

Another common factor is the argument of silence, where if we don't know about something then it hasn't happened. And, when we discover something showing others having the same knowledge or techniques -- like fragments of evidence in Roman wrestling that mirror techniques practiced today -- we are surprised.

In physical performance, we have only our selves and our near-history to evaluate against, and when a fragment of the past is discovered, we are surpised to see the similarity of methods. The gift of motion pictures, and now video, will help mitigate this to a point. But, it will take people to actually go back through those visual archives, otherwise, we're back to the argument of silence -- people will assume it (whatever "it" is) has never been done before, or it could not have been done.

Our technology has changed, we have night vision devices and drones that launch missiles, but our bodies have not changed. Because of the sameness of our bodies, you can expect a level of sameness (or similarity) of techniques across history.